The Hall effect, named after the American physicist Edwin Herbert Hall (1855-1938), produces a potential difference across a conductor carrying an electric current when a magnetic field is applied in a direction perpendicular to that of the current flow. It is employed in Hall sensors for the measurement of magnetic fields. The conductor of a Hall sensor is usually a plate of an electrically conducting material provided on opposite edges with electrodes serving to apply an operation voltage, which makes an electric current flow through the plate in the direction from one electrode to the other. In the presence of a magnetic field with a component that is perpendicular to the plane of the plate, a Hall voltage is generated within the plate in a direction that is orthogonal both to the current and to this component of the magnetic field and can be detected by means of further electrodes provided at opposite edges of the plate in the direction across the current. A Hall sensor can be realized as a semiconductor device with integrated circuit and manufactured in CMOS technology, for example.
Vertical Hall sensors comprising a conductor plate that is perpendicular to an upper chip surface are sensitive to magnetic fields having a component normal to the plate and parallel to the chip surface and are therefore important in products like rotary encoders and accelerometers which require a two-dimensional or three-dimensional measurement of the magnetic field. The integration of Hall sensors for two or three spatial dimensions together with the related circuits on the same chip allows a production of compact and reliable products within a CMOS process. Since conventional semiconductor technologies are mainly directed to the production of layered structures that are coplanar with the chip surface, the vertical arrangement of the conductor plate of a semiconductor Hall sensor requires special solutions.
R. S. Popovic: “The vertical Hall-effect device”, IEEE Electron Device Letters EDL-5 (1984), page 357, describes a vertical device having an arrangement of contacts on the chip surface.
EP 0 1 129 495 B1 describes an integrated Hall device comprising a plate-like active region integrated in a doped silicon substrate perpendicularly to a structured substrate surface, which is provided with contacts for the application of an operation voltage and the detection of a Hall voltage. The active region is doped by an implantation through sidewalls of trenches, which are subsequently filled. The active region is electrically insulated from the rest of the substrate by a pn-junction.
EP 0 1 438 755 B1 describes a vertical Hall sensor comprising a plate-like electrically conductive region extending into a substrate perpendicularly to the surface of the substrate. A small outer surface of the plate is located in the substrate surface and is provided with contacts for the application of an operation voltage and the detection of a Hall voltage.
WO 2007/0 121 885 A1 describes a vertical Hall sensor comprising a semiconductor substrate having a main surface, a semiconductor region of a first type of conductivity, which extends from the main surface into the substrate, a plurality of contacts on the main surface in the area of said semiconductor region, and a plurality of non-conducting barrier regions, which extend from the main surface into said semiconductor region. The barrier regions are disposed between each pair of neighboring contacts and are provided to keep an operating current that flows between the contacts away from the main surface. The resistance is increased, since the current path around the barrier regions is longer.
U.S. Pat. No. 6,255,190 B1 describes a method of forming very deep pn-junctions by means of deep trench sidewall predeposition technology without using epitaxy or extensively high temperature processing. If the trenches have a sufficient longitudinal extension and a sufficient depth, an n-type region surrounded with p-type semiconductor material can be established by this method and used to realize a Hall sensor. The n-type region is obtained by an implantation of n-type dopants into sidewalls of deep trenches and encompasses the trenches. It serves as a vertical electrically conductive plate of the Hall sensor and, if a sensing contact is placed outside the area delimited by the trenches, also as contact pillar or sinker contact to connect the surface contact with the bottom of the plate that is formed between the trenches.